How Storage vMotion works?
Storage vMotion enables live migration of running virtual machine disk files from one storage location to another with no downtime or service disruption.
- This simplifies storage array migration or storage upgrades.
- Dynamically optimize storage I/O performance.
- Efficiently utilize storage and manage capacity.
- Manually balances the storage load.
Storage vMotion process:
- vSphere copies the non-volatile files that make up a VM: vmx, swp, logs & snapshots.
- vSphere starts a ghost or shadow VM on the destination datastore. Because the ghost VM does not yet have a virtual disk (that hasn't been copied over yet), it sits idle waiting for its virtual disks.
- Storage vMotion first creates a destination disk. Then a mirror device - a new driver that mirrors I/Os between source & destination.
- I/O mirroring in place, vSphere makes a single-pass copy of virtual disks from source to destination. As the changes are made to the source, the mirror driver ensures that changes are also reflected at the destination.
- When the virtual disk copy completes, vSphere quickly suspends & resumes in order to transfer control over to the ghost VM on the destination datastore.
- Files on the source datastore are deleted.
Virtual mode RDM storage vMotion - if you want to migrate only the vmdk mapping file - select “Same Format as source”.
Physical mode RDMs are not affected.